Typical networks such as an Internet network may be accessed through a variety of ways (GPRS, WLAN, ADSL modem, etc.). In addition, many access technologies support multiple QoS flows (GPRS, ADSL, RSVP, etc.). For the same time, the same user equipment is often used to access different networks. A typical illustration is a GPRS network where a user equipment may be connected to the Internet or an Intranet using different Access Points. GPRS is the packet technology used in GSM and in UMTS (using WCDMA (Wideband Code Division Multiple Access)radio)). In GPRS, each QoS flow is associated to a PDP context (logical connection from user equipment to external network).
In a PDP (Packet Data Protocol) Context Activation Procedure as shown in FIG. 1, an MS (Mobile Station) sends an Activate PDP Context Request message comprising PDP Type, PDP Address, APN (Access Point Name) and QoS (Quality of Service) Requested to an SGSN (Serving GPRS Support Node) in a PLMN (Public Land Mobile Network). QoS Requested indicates the desired QoS profile. The SGSN validates the Activate PDP Context Request optionally using PDP Type, PDP Address and APN.
If a GGSN (Gateway GPRS Support Node) address can be derived, the SGSN sends a Create PDP Context Request message comprising PDP Type, PDP Address, APN and QoS Negotiated to the affected GGSN. The GGSN may use the APN to find an external network. A Selection Mode indicates whether a subscribed APN was selected, or whether a non-subscribed APN sent by the MS or a non-subscribed APN chosen by the SGSN was selected. The GGSN may use the Selection Mode when deciding whether to accept or reject the PDP context activation. For example, if an APN requires subscription, then the GGSN is configured to accept only the PDP context activation that requests a subscribed APN as indicated by the SGSN with Selection Mode. The GGSN creates a new entry in its PDP context table and creates a Charging Id. The new entry allows the GGSN to route PDP PDUs (Packet Data Units) between the SGSN and the external PDP network and to start charging. The GGSN returns a Create PDP Context Response message comprising PDP Address, QoS Negotiated and Charging ID to the SGSN.
If QoS Negotiated received from the SGSN is incompatible with the PDP context being activated, then the GGSN rejects the Create PDP Context Request message.
The SGSN returns an Activate PDP Context Accept message to the MS. The SGSN is now able to route PDP PDUs between the GGSN and the MS and to start charging.
GPRS can support different QoS flows, each corresponding to a PDP context, for a unique PDP address (e.g. Ipv4 or Ipv6 address). In 3GPP Release 99 the QoS mechanism uses a set of filters called Traffic Flow Template (TFT) and information in the IP header, such as Type of Service (ToS) field or UDP (User Datagram Protocol) port number in order to determine to which PDP context an IP packet belongs.
The MS maps uplink packets to the proper PDP context, and GGSN maps downlink packets to the proper PDP context using TFT. It is to be noted that the MS configures the GGSN TFT.
While such QoS mechanism allows to differentiate traffic, it may not always be easy to use for various reasons:                applications do not always use fixed port numbers,        end-to-end encryption may render the UDP port number inaccessible for the GGSN,        ToS values are selected by the operator, so an application may have different ToS values in different networks, and/or        ToS values may be changed by edge routers at the point of interconnection between two ISPs (Internet Service Providers).        
A typical application example is an H323 call. Relying on the port number is not useful since some H323 family protocols e.g. H245 use dynamic port. Using the port number will be just impossible if encryption is used.
Usually, the end point of an IP connection of the user equipment is a server in an IP network, which is controlled by the operator of the IP network, for example a Call Server, or the end point is a server in the Internet or Intranet, which is not controlled by the IP network operator. However, communication may also be established between two user equipments (e.g. VOIP call), connected through different operators' networks.
Hence, the general problem is how to properly configure QoS for applications which may connect through different access and to different networks, in particular, the QoS parameters used by the access technology, the filter used to select the proper QoS flow, and QoS parameters (e.g. ToS) used in the network where the connection is established. An additional problem is how to set filters for applications which do not use fixed port number, or for which the port number cannot be read due to encryption. A further problem is that ToS setting is most often proprietary.